Shimano Saint RD-M800 Rear DRLR 135mm Question.

Hey Guy's. I want to pull the trigger on Two of these Der.'s. Or One Hone
and One Saint Der. I just bought almost the Whole Saint Package which
Included the Rear Der. I just want a couple of BackUp's as the price
is so cheap. I bought the set for my next build. My Rear Hub is a 150mm.
Shifter's will be XTR 8 Speed.

Question: The Saint Der on Sale is listed as a 135mm.Can I use this Der.
as Long as I have my 150mm Axel?

Queston #2: Why does the Hone Der. Not state the spacing like the Saint
does?

Question#3:The "Saint M801 Rear Derailleur f/135mm Frame" is listed as "not
rapidrise". So the M800 is Rapid Rise? What does the "f" sand for in f/135?

All this info come's from Jenson's Site.

I assume my problem would be the same with either,regarding the Axel. I have been told that
the Hone work's fine,however I have never ran this setup before. I am just trying
to get my Fact's straight,sorry I'm a little confused.